1. Field of the Invention
The present invention relates to an ion conductive film and a fuel cell using the same.
2. Description of the Related Art
The conventional methanol fuel cell can be classified according to the method of supplying the liquid fuel: a liquid supply type and a gasified fuel supply type. In the fuel cell of the gasified fuel supply type, the electrode reaction is carried out between the electrode and the gasified fuel. As a result, it is possible to obtain a high performance with a high reactivity. On the other hand, the system is highly complex, making it difficult to be miniaturized.
When it comes to the fuel cell of a liquid supply type, the system is rendered relatively simple, compared with the gasified fuel supply type. However, since the electrode reaction is takes place between the electrode and the liquid fuel, the reactivity is low, leading to the problem of low performance. The liquid fuel cell utilizes the capillary action for the supply of fuel, in a liquid state, to the fuel electrode and, thus, does not require a pump or the like. Therefore, the liquid fuel cell of this type can be miniaturized. However, the electrode reaction is weak and, thus, is low in performance.
In addition to the problems described above, the greatest problem inherent in the fuel cell is that, where a proton conductive solid polymer film, such as a film of perfluorosulfonic acid available under the trade name “Nafion” from Du Pont Inc., USA, is used as an electrolytic membrane, generated is a cross-over problem caused by the permeation of an organic liquid fuel, such as methanol, through the electrolytic membrane, reaches the electrode of the oxidizing agent. Where this “cross-over” phenomenon has taken place, the supplied liquid fuel reacts directly with the oxidizing agent, resulting in failure to output the energy as the electric power. It follows that a decisive problem is generated that it is impossible to obtain a stable output.